This patent application is related to U.S. patent application Ser. No. 553,316 entitled Cross Bearer Arrangement for Slotted Center Sill by applicants John H. Spence and Phillip G. Przybylinski and a patent application filed on the same date as this application and entitled Double Groove Center Sill by applicants Henry K. Wiger and Manfred Katz.
1. Field of Invention
This improvement relates to the field of flat railway cars having a torsionally flexible center sill to accommodate conditions occurring with the use of single axle wheel trucks which, due to track irregularities, could cause operating problems.
2. Description of the Prior Art
In the present improvement the center sill and associated structure is made torsionally flexible by the use of a slotted sill and other associated structures which accommodate operating conditions occurring as a result of track conditions. Slotted center sills are old in the prior art as indicated in Fenstermacher et al. U.S. Pat. No. 2,217,683 which includes a rigid structure having no torsional flexibility, the utilization of the slot merely being for the purpose of taking weight out of the structure. The Miller et al. U.S. Pat. No. 3,777,671 also discloses a rigid underframe having a sliding sill with a transverse divider plate. Neither of these patents relate to the present improved design.